Composite resin composition

ABSTRACT

The invention provides a composite resin composition comprising aliphatic polyester resin (component A) having aliphatic hydroxycarboxylic acid units, one or more biomass material (component B) selected from the group consisting of cellulose, lignocellulose and starch and unsaturated carboxylic acid or a derivative thereof (component C), wherein the composite resin composition comprises a component obtained by covalently bonding a portion or the whole of component A and component B through component C. On processing into various formed items, the composite resin composition of the invention exhibits excellent tensile strength and other physical properties and processability and simultaneously has good biodegradability, and enable biomass materials of low added value to apply to high added value uses in a large amount.

This application is a divisional of application Ser. No. 09/134,382filed Aug. 14, 1998 allowed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composite material compositioncomprised of a constitutional element having biodegradability, and morespecifically relates to a composite resin composition which has highprocessing ability on processing said composition, provides resultingprocessed articles having an excellent mechanical strength andbiodegradability, and can be effectively utilized for a film, sheet,tray and other one-way formed articles, furniture parts, constructionmaterials, interiors for motor vehicle and household electricalappliances, and housing applications.

2. Description of the Related Art

Cellulose, wood, starch and other biomass materials have poorthermoplasticity and powdered materials, in particular, have beendifficult to process by hot-press plastic forming as intact into boardsand sheets.

Consequently, wood flour, in particular, which is a waste matter andexists on a huge amount is limited to utilization in a field of lowadded value such as straw mulching for cattle breeding and other farmand dairy materials and fillers. In the extreme cases, wood flour isburned out without utilization.

Further, the wood flour was utilized also in Japan until several yearsago as a raw material of activated carbon. The utilization wasconsidered useful in view of environmental conservation. However, due tolow degree of processing, import of the activated carbon from South EastAsia and China is now increased and domestic products are extremelydecreased.

Also as to the cellulose based waste, effective utilization of wastepaper is not necessarily progressed. Development of new techniques forthe practical application of waste paper is now desired in relation tofill out and effective date of recycle act which is now focusedattention(on waste paper and paper box, in the year 2000 A.D.).

As to starch, new development of practical use for various purposesother than foods has been desired in view of the present situation onthe balance of world-wide demand or in consideration that there is spacefor increasing supply of starch.

From a still higher standpoint, a way of thinking that an organicmaterial system using plant resources and cereals as a raw material willbe required in the near future in order to apply a brake on the use ofpetroleum is beginning to sprout. As a fundamental response to suchsituation, it should be needed to have a sense of problem that anapplication technique of a biomass material will be steadily made upfrom the base.

Consequently, various investigations have been carried out on ahigh-grade utilization or a large-scale application of biomassmaterials. A typical example includes a molding material obtained bymelt-kneading a thermoplastic resin with wood flour.

However, o n the basis of the conventional technique, such a moldingmaterial prepared from thermoplastic resin and wood flour has beenunsatisfactory to dispersibility, compatibility, adhesion ability ofwood flour surface to matrix resin and mechanical property.

As a result of an intensive investigation in vie w of these problems,the present inventors have found that these problems can be solved byemploying a modified resin for the matrix resin. That is, the presentinventors have disclosed in Japanese Laid-Open Patent SHO 62-039642 atechnique concerning a composite resin composition which is obtained byformulating a specific proportion of modified polyolefin, cellulosicmaterial and specific graft compound, is extremely excellent inmechanical strength and also excellent in transparency and smoothnessand suitable for interiors such as films, sheets and furniture.

Many investigations have been conducted on th e application of thetechnique. As a result, an artificial wood of markedly high durabilityprepared by extrusion-forming a wood flour/thermoplastic resin compositekneaded material has come to be effectively used as a residential part.

These techniques use wood and other biomass materials as a filler andemploy polypropylene, polyethylene, polyvinyl chloride, ABS resin andother general purpose resins for a matrix resin. It is thus verysignificant when good durability is required.

However, in consideration of the final waste disposal treatment afterfinishing use, the waste remains semipermanently in the environment whenlandfilled and emits hazardous wastes into the environment whenincinerated.

SUMMARY OF THE INVENTION

One of the subject to be solved by the invention is to provide adegradable composite resin composition which comprised of abiodegradable resin and biomass material and is remarkably improved inthe dispersibility of the biomass material into the biodegradable resin,compatibility of the biodegradable resin and the biomass material,adhesion of the surface of biomass material to the matrix biodegradableresin, mechanical properties in the processing time and thermal flowprocessing ability; a preparation process of the degradable compositeresin composition; and a molding material comprised of said degradablecomposite resin composition.

Another subject to be solved by the invention is to provide a moldingmaterial which is comprised of a biodegradable resin and biomassmaterial and, when in consideration of the final waste disposal stepafter finishing the use of product, degrades without remaining in theenvironment on land-filling and emits no hazardous material into theenvironment on incineration.

A further subject to be solved by the invention is to provide a moldingmaterial which is comprised of a biodegradable resin and biomassmaterial and, when in consideration of the final waste disposal stepafter finishing the use of product from disposable application toconsumer durable goods such as construction materials, motor vehicleinteriors and exteriors, housing of household electric appliances andmiscellaneous parts, degrades without remaining in the environment onland-filling and emits no hazardous material into the environment onincineration.

A still further subject to be solved by the invention is to provide amolded article, artificial wood, container, film, sheet, tray and foamobtained by processing a composite resin composition which is comprisedof a biodegradable resin and biomass material and, when in considerationof the final waste disposal step after finishing the use of the product,degrades without remaining in the environment on land-filling and emitsno hazardous material into the environment on the incineration.

The present inventors have carried out intensive investigation in orderto develop a composite composition of a biodegradable resin and biomassmaterials such as biodegradable wood flour. As a result, they have foundthat unsaturated carboxylic acid or derivative thereof, aliphaticpolyester having aliphatic polyhydroxycarboxylic acid units and biomassmaterials such as wood flour or starch are heated and kneaded to obtaina composite resin composition which provides a molded article having ahigh melt flowability in the processing step, good mechanical strength,and high smoothness and gloss on the surface. Thus, the presentinvention has been completed on the basis of the information.

That is, an aspect of the invention is a preparation process of acomposite resin composition comprising heating and kneading a mixture of5-95% by weight of aliphatic polyester resin (component A) havingaliphatic hydroxycarboxylic acid units and 95-5% by weight of one ormore biomass materials (component B) selected from the group consistingof cellulose, lignocellulose and starch, and 1-30 parts by weight for100 parts by weight of component A of unsaturated carboxylic acid or aderivative thereof (component C) in the presence of a radical generator.

Another aspect of the invention is a composite resin compositioncomprising a mixture of 5-95% by weight of aliphatic polyester. resin(component A) having aliphatic hydroxycarboxylic acid units and 95-5% byweight of one or more biomass materials (component B) selected from thegroup consisting of cellulose, lignocellulose and starch, and 1-30 partsby weight for 100 parts by weight of component A of unsaturatedcarboxylic acid or a derivative thereof (component C), wherein saidcomposite resin composition comprises a component obtained by covalentlybonding a portion or the whole of component A and component B throughcomponent C.

A further aspect of the invention is a preparation process of acomposite resin composition comprising obtaining modified aliphaticpolyester (component D) having aliphatic hydroxycarboxylic acid units byheating and reacting 100 parts by weight of aliphatic polyester resin(component A) having aliphatic hydroxycarboxylic acid units and 1-30parts by weight of unsaturated carboxylic acid or a derivative thereof(component C) in the presence or absence of a solvent in the presence ofa radical generator, and successively heating and kneading a mixture of5-95% by weight of a mixture (component E) of 0-95% by weight ofcomponent A and 100-5% by weight of component D, and 95-5% by weight ofone or more biomass materials (component B) selected from the groupconsisting of cellulose, lignocellulose and starch.

A still another aspect of the invention is a composite resin compositioncomprising a mixture (component E) of 0-95% by weight of aliphaticpolyester resin (component A) having aliphatic hydroxycarboxylic acidunits and 100-5% by weight of modified aliphatic polyester resin(component D) having aliphatic hydroxycarboxylic acid units which isobtained by reacting 100 parts by weight of component A with 1-30 partsby weight of unsaturated carboxylic acid or a derivative thereof(component C), and one or more biomass materials (component B) selectedfrom the group consisting of cellulose, lignocellulose and starch,wherein said composite resin composition comprises a component obtainedby covalently bonding a portion or the whole of component A andcomponent B through component C and component B is 5-95% by weight ofcomponent B and component D or component E.

A still further aspect of the invention is processed articles,artificial wood, container, film, sheet, tray and foam comprised of thecomposite resin composition of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The composite resin composition of the invention can be obtained byheating, kneading and reacting all together aliphatic polyester resin(component A) having aliphatic hydroxycarboxylic acid units, biomassmaterial (component B) and unsaturated carboxylic acid or a derivativethereof (component C) (one step process). In another process, aliphaticpolyester resin (component A) having aliphatic hydroxycarboxylic acidunits is heated and reacted with unsaturated carboxylic acid or aderivative thereof (component C) in the presence of a radical generatorto obtain modified aliphatic polyester resin (component D) havingaliphatic hydroxycarboxylic acid units and successively component D or,when necessary, a mixture of component D and component A is heated andkneaded with biomass material (component B) (two step process).

The raw materials used for the invention will be illustrated first.

The aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid unit which can be used for the invention isaliphatic homopolyester, copolyester or a mixture thereof which containaliphatic hydroxycarboxylic acid units in the polymer. No particularrestriction is imposed upon the amount of aliphatic hydroxycarboxylicacid units in the polymer. The amount is preferably 50% by weight ormore. When the aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units is a copolymer, the arrangement mode can beany of random copolymer, alternate copolymer, block copolymer and graftcopolymer.

That is, the aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units includes the following aliphatic polyester,

1) Aliphatic hydroxycarboxylic acid homopolymer, for example, polylacticacid or poly-ε-caprolactone,

2) A copolymer of aliphatic hydroxycarboxylic acid with other aliphatichydroxycarboxylic acid, for example a block copolymer of polylactic acidand poly-ε-caprolactone, a random copolymer of lactic acid and glycolicacid,

3) A copolymer with aliphatic hydroxycarboxylic acid, aliphaticpolyhydric alcohol and aliphatic polycarboxylic acid or anhydridethereof, for example, a block copolymer of polylactic acid andpolybutylene succinate, a random copolymer of lactic acid, succinic acidand ethylene glycol, and

4) A star polymer having aliphatic hydroxycarboxylic acid and aliphaticpolyhydric alcohol, aliphatic polycarboxylic acid or polysaccharide as anucleus, and a polymer which is obtained by combining said star polymerwith aliphatic polyhydric alcohol or aliphatic polycarboxylic acid, forexample, a star polymer having glycerol, pentaerythritol,1,2,3,4-butanetetracarboxylic acid or ethylcellulose as a nucleus andpolylactic acid as a side chain and a polymer which is obtained bycombining said star polymer with pentaerythritol or1,2,3,4-butanetetracarboxylic acid.

No particular restriction is imposed upon the aliphatichydroxycarboxylic acid which is a raw material of aliphatic polyesterresin (component A) having aliphatic hydroxycarboxylic acid units.Exemplary aliphatic hydroxycarboxylic acids include, for example,glycolic acid, lactic acid, 3-hydroxybutyric acid, 4-hydroxybutyricacid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid and 6-hydroxycaproicacid, and further include cyclic ester of aliphatic hydroxycarboxylicacid, for example, glycolide which is a dimer of glycolic acid, lactidewhich is a dimer of lactic acid and ε-caprolactone which is a cyclicester of 6-hydroxycaproic acid. These aliphatic hydroxycarboxylic acidscan be used as a mixture. When aliphatic hydroxycarboxylic acid hasasymmetric carbon atoms, D-isomer and L-isomer can be used singly,respectively. A mixture of these isomers, that is , racemic isomer canalso be used.

No particular restriction is imposed upon the aliphatic polycarboxylicacid or the anhydride thereof which is a raw material of aliphaticpolyester resin (component A) having aliphatic hydroxycarboxylic acidunits used in the invention. Representative aliphatic polycarboxylicacids and anhydrides include, for example, oxalic acid, succinic acid,malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, undecane diacid, dodecane diacid and otheraliphatic dicarboxylic acids; 1,2,3,4,5,6-cyclohexanehexacarboxylicacid, 1,2,3,4-cyalopentanetetracarboxylic acid,tetrahydrofuran-2R,3T,4T,5C-tetracarboxylic acid,1,2,3,4-cyclobutanetetracarboxylic acid,4-carboxy-1,1-cyclohexanediacetic acid, 1,3,5-cyclohexanetricarboxylicacid, (1α,3α,5β)-1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid andother three functional or more aliphatic or alicyclic polycarboxylicacids, or anhydride of these compounds. These aliphatic polycarboxylicacids or anhydrides can be used as a mixture when necessary. When thesecompounds have an asymmetric carbon in the molecule, D-isomer andL-isomer can be used singly, respectively. A mixture of D-isomer andL-isomer, that is, a racemic isomer can also be used.

No particular restriction is imposed upon aliphatic polyhydric alcoholswhich is a raw material of aliphatic polyester resin (component A)having aliphatic hydroxycarboxylic acid units in the invention. Specificpolyhydric alcohols which can be used include, for example, ethyleneglycol, diethylene grlycol, triethylene glycol, polyethylene glycol,propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol,3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentylglycol, polytetramethylene glycol, 1,4-hexanediol,cyclohexanedimethanol, hydrogenated bisphenol-A and other diols;glycerol, pentaerythritol, dipentaerythritol, trimethylolethane,trimethylolpropane, inositol and other three or more functional polyols,and further include cellulose, cellulose nitrate, acetyl cellulose,nitrocellulose; cellophane, viscose rayon, cupra and other regeneratedcellulose, hemicellulose, starch, amylopectin, dextrin, dextran,glycogen, pectin, chitin, chitosan and derivatives of these matters andpolysaccharides. These aliphatic polyhydric alcohols can be used as amixture when necessary. When these aliphatic polyhyudric alcohols haveasymmetric carbon in the molecule, D-isomer and L-isomer and D-isomer,that is, a racemic isomer can also be used.

The above various aliphatic homopolyester or copolyester can be usedaliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units, and the polyester having a lactic acidunits is preferred. More preferably, 50% by weight or more lactic acidunits are contained in the polyester.

Specific examples of aliphatic polyester resin composition having lacticacid units which can be preferably used in the invention includepolylactic acid, random or block copolymer of lactic acid and6-hydroxycaproic acid, block copolymer of polylactic acid andpolybutylene succinate, a star polymer having pentaerythritol,1,4-butanetetracarboxylic acid or ethyl cellulose as a nucleus andpolylactic acid as a side chain and a polymer which is obtained bycombining said star polymer with pentaerythritol or 1,4-butanediol.

No particular restriction is imposed upon the preparation process ofaliphatic polyester resin having aliphatic hydroxycarboxylic acid units(component A) of the invention. Component A can be prepared by knownprocesses, for example, direct dehydration polycondensation andring-opening polymerization.

For example, U.S. Pat. No. 5,310,865 has disclosed a preparation processof homopolymer or copolymer of aliphatic hydroxycarboxylic acid bydirect hydration polycondensation and not by ring-openingpolymerization. In the process, lactic acid and when necessary, otheraliphatic hydroxycarboxylic acid are subjected to azeotropic dehydrationcondensation preferably in the presence of an organic solvent, diphenylether based solvent in particular, and more preferably, are progressedthe polymerization by removing water from the azeotropically distilledsolvent and returning the substantially anhydrous solvent to thereaction system. Such process can provide homopolymer or copolymer ofaliphatic hydroxycarboxylic acid wich is suited for use in theinvention.

Siutable molecular weight regulator, branching agent and other modifierscan also be added in the preparation of aliphatic polyester (componentA) resin having aliphatic hydroxycarboxylic units.

No particular restriction is imposed upon the molecular weight andmolecular weight distribution of aliphatic polyester resin (component A)having aliphatic hydroxycarboxylic acid units of the invention. In viewof thermal and mechanical properties, the weight average molecularweight (Mw) is preferably 30,000 or more, more preferably 50,000 to1,000,000.

The biomass materials (component B) used in the invention are one ormore substances selected from cellulose, lignocellulose and starch.

Exemplary cellulose which can be used includes alpha fiber flockobtained by alkali-treating wood pulp and subjecting to mechanicalchopping, cotton linter and cotton flock prepared from cotton seed, andrayon silk-cut rayon flock.

Exemplary lignocellulose includes lignocellulose fiber andlignocellulose powder, and can practically exemplify wood pulp, refinergraft pulp (RGP), paper pulp, waste paper, crushed wood chip, wood flourand fruit hull powder.

No particular restriction is put on the shape of these cellulose andlignocellulose materials and fiber or powder can be preferably used.

Representative wood flour which can be used includes, for example,ground products, saw dust and shavings of pine, fir, bamboo, bagasse,oil palm stem and popula, and fruit hull powder includes ground productsof fruits of walnut, peanuts and palm. When wood flour is used, the woodflour is finely pulverized as fine as possible to preferably removeentanglement of the fiber each other. However, in view of complexworking and economy, powder having a particle size of 20 to 400 mesh isusually used.

RGP and wood flour are preferred in particular. When RGP is used, drysplit yarn is preferably used after untying entanglement of the fibereach other.

Exemplary starch which can be widely used in the invention includes, forexample, corn starch, potato starch, taro starch, tapioca starch andlightly acetylated products of these starches. Starch is usuallyobtained in the form of granule and can be used as intact.

The unsaturated carboxylic acid or a derivative thereof (component C)which can be used in the invention preferably includes, for example,maleic acid, maleic anhydride, nadic acid, itaconic acid itaconicanhydride, citraconic acid, citraconic anhydride, crotonic acid,isocrotonic acid, mesaconic acid, angelica acid, sorbic acid and acrylicacid. Maleic anhydride is preferred in particular. Derivatives of theunsaturated carboxylic acid which can be used include metal salt, amide,imide, and ester of the above unsaturated carboxylic acids. Theseunsaturated carboxylic acid or anhydride can be used as a mixture.

No particular restriction is imposed upon the radical generator used inthe invention so long as the generator accelerates the reaction betweenthe aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units and unsaturated carboxylic acid or aderivative thereof (component C). Exemplary radical generators which canbe suitably used include, for example, benzoyl peroxide, louroylperoxide, cumene hydroperoxide,α,α'-bis(t-butylperoxydiisopropyl)benzene, di-t-butyl peroxide,2,5-di(t-butylperoxy)hexane, p-chlorobenzoyl peroxide, acetyl peroxide,1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylperoxypivalate,t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzozte,bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropylperoxydicarbonate,t-butylperoxyisopropylcarbonate, and other peroxides; andazobisisobutyronitrile and other azo compounds.

Next, the preparation process of the composite resin composition of theinvention will be illustrated in detail.

One of the preparation process of the invention is a process for heatingand kneading aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units, biomass material (component B) andunsaturated carboxylic acid or a derivative thereof (component C) alltogether in the presence of a radical generator (one step process).

As to the content of component A and component B, the content ofcomponent A is 5-95% by weight, preferably 10-90% by weight for thetotal ammount of component A and component B. When the content ofcomponent A exceeds 95% by weight, the content of component B becomestoo small and reinforcing effect of component B unfavorably decreases.On the other hand, when the content of component A is less than 5% byweight, the content of component B becomes too much and impairs strengthof the molded articles or unfavorably provides a defective moldedarticle having poor transparency and gloss.

The amount of component C is 1 part by weight or more, preferably 1-30parts by weight for 100 parts by weight of component A. When the amountof component C is less than 1 part by weight, a covalently bondedcomponent of component A and component B through component C cannot beobtained or obtained in an unsufficient amount, if obtained andmechanical strength and hot-melt flowability which are expected for themolded article cannot be obtained. On the other hand, when the amount ofcomponent C exceeds 30 parts by weight, further improved mechanicalstrength cannot be obtained and the molded article is liable to becomebrittle.

No particular restriction is imposed upon the amount of radicalgenrator. The radical generator is commonly used 0.01-1 part by weightfor 100 parts by weight of component A.

In the preparation process of the invention, heating and kneading can becarried out by conventionally known procedures. For example. By usingBanbury mixer, Henschel mixer and other mixers, roll mill having pluralrolls, kneader and various types of extruders, the materials are heatedand kneaded at a temperature higher than the melting point of componentA, preferably at 140-240° C., more preferably at 160-200° C., for 5-50minutes, preferably for 10-30 minutes. Rotational velocity of a kneaderis usually 30-200rpm, preferably 50-150rpm. High temperature which leadsto scorching of component B should be avoided.

No particular restriction is out upon the order of addition on theheating and kneading of each component. Generally component B andcmponent C are preferably added to the molten state of component A.

Furthermore, heating and kneading are preferably carried out in an inertgas atmosphere so as to avoid contamination of moisture from outside ofthe system, and can also be carried out while ventilating or bubbling aninert gas.

Another preparation process of the invention is to heat and reactaliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units with unsaturated carboxylic acid or aderivative thereof (component C) in the presence of a radical generatorin the presence or absence of a solvent to obtain modified aliphaticpolyester resin (component D) having aliphatic hydroxycarboxylic acidunits, and successively to heat and knead said modified aliphaticpolyester resin (component D) having aliphatic polyhydroxycarboxylicacid units or a mixture of component D and aliphatic polyester resin(component A) having aliphatic hydroxycarboxylic acid units with biomassmaterials (component B) (two step process).

In this case, the amount of component C for the amount of component Aand the amount of the radical generator is the same as the above onestep process.

The procedures for reaction component A with component C are the same asthe above heating and kneading procedures.

Further, component A and component C can also be reacted in the presenceof a solvent. A high-boiling solvent capable of dissolving component Ais preferably used. Reaction temperature is 140-240° C., preferably160-200° C. and reaction time is 1-5 hours. After finishing thereaction, the solvent is removed by distillation, reprecipitation orother known methods to obtain component D.

The addition ratio of component C in modified aliphatic polyester resin(component D) having aliphatic hydroxycarboxylic acid unit is 0.1-15% byweight, preferably 0.5-10% by weight.

Thus obtained component D can be heated and kneaded as intact withcomponent B. However, in consideration of a mixing ratio of component Band component D, a mixture (component E) obtained by diluting componentD with component A can also be used when necessary. That is, a mixture(component E) of component D and component A containing 0-95% by weightof component A can also be used.

The procedures for heating and kneading component D or component E andcomponent B can also be carried out similarly to the above one stepprocess.

In such a case, the proportion of component D or component E tocomponent B is that component D or component E occupies 5-95% by weightfor total amount of component D or component E and component B,preferably 10-90% by weight. When the proportion of component D orcomponent E exceeds 95% by weight, the proportion of component B becomestoo small and reiforcing effect of component B unfavorably decreases. Onthe other hand, when the proportion of component D or component E isless than 5% by weight, the proportion of component B becomes too much,and leads to unfavorably provide molded articles having deficiency instrength and poor transparency and gloss.

In the preparation process of the composite resin composition of theinvention and below described various processing methods, lubricant,antioxidant, colorant, antistatic agent, plasticizers and othermicellaneous additives can be suitably added when necessary.

The composite resin composition thus obtained is excellent in themechanical strength and hot-melt flowability in the processing step andcan provide molded articles having biodegradability and excellentsmoothness and gloss.

The composite resin composition of the invention comprises a componentobtained by covalently bonding a portion or more of aliphatic polyesterresin (component A) having aliphatic hydroxycarboxylic acid units and aportion or more of biomass materials (component B) through unsaturatedcarboxylic acid or a derivative thereof (component C).

The presence of a component obtained by covalently bonding compound Aand component B through component C brings the above various propertiesand particularly contributes to the improvement in tensile strength andheat flowability on processing the composite resin composition of theinvention into molded articles.

The composite resin composition of the invention can be suitablyprocessed into desired shape by means of pressure molding, film forming,vacuum forming, extruding and injection molding to prepare variousformed items.

Consequently, the composite resin composition of the invention has anextremely high utilization in industry. That is, the present inventioncan provide processed items having excellent properties and when inconsideration of the final waste disposal step after finishing the useof the product, degrades without remaining in the environment onland-filling and emits no hazardous material into the environment on theincineration.

The present invention can provide processed items, artificial wood,container, film, sheet, tray and foam which are excellent in tensilestrength, tensile elongation at break, tensile modulus and othermechanical strengths.

The composite resin composition of the invention can be effectively usedas a stock for various film and sheet materials, disposable formed itemssuch as container, pipe, square bar, rod, artificial wood, tray,concrete panel and foam, furniture, construction material, motor vehicleinteriors and exteriors, household electronic housing, civil engineeringand construction materials, materials for agriculture, dairy forming andmarine products industry, recreational materials and sporting materials.

Thus, the present invention enables biomass materials which haveconventionally low added value utilization to serve for high gradeutilization and moreover, composite resin composition which is excellentin strength properties and has biodegradability can be provided withease in industry at a relatively moderate price.

EXAMPLES

The examples of the invention will be illustrated hereinafter. However,the invention is not construed to be limited by the method and equipmentdescribed below.

In the examples, physical properties were measured by following methods.

1) Tensile strength, elongation at break and tensile modulus Measured inaccordance with JIS K-6732.

2) Melt viscosity and heat flow temperature Measured by using FlowTester CFT-C.

Examples 1-10

Into a beaker, 23 parts by weight of powdery polylactic acid having aweight average molecular weight of 130,000 (PLA: manufactured by MitsuiChemicals Inc.), 2.3 parts by weight of maleic anhydride and 0.08 partsby weight of dicumyl peroxide were weighed, thoroughly mixed, andimmediately poured into a 30 ml volume chamber of a kneader. The kneaderused was a labo-plastomill manufactured by Toyo Seiki Co. The plastomillwas previously controlled at 160° C. and stirring blades were rotated ata rate of 30 rpm to the reverse direction each other. After charging,the rate of the stirring blades was immediately increased to 70 rpm andthe mass was reacted by kneading at 160° C. for 15 minutes. Afterfinishing the reaction, the reaction mass was immediately discharged andcooled. After cooling sufficiently, the reaction mass was pulverizedwith a plastic grinder and used in the successive experiments as maleicanhydride modified polylactic acid (MPLA-1).

MPLA-1 thus obtained was purified by dissolving in chloroform, pouringinto a large amount of n-pentane to carry out precipitation, filteringthe precipitate and drying the filter cake. The addition ratio of maleicanhydride to PLA was measured by titration. The addition ratio was 1.1%by weight. The titration was carried out by the following procedures.That is, 0.2 g of a sample of MPLA-1 was purified by the procedure abovedescribed and dissolved in 50 ml of a 1 1 by volume mixture ofchloroform and ethanol and was titrated by N-NaOH ethanol solution. A1:1 mixture of brom thymol blue and phenol red was used as an indicator.At the endpoints, the color was changed from yellow to light violet. Thetitration was carried out 5 times and the average value was employed.The addition ratio of maleic anhydride was calculated from the followingequation,

    Addition ratio of maleic acid (%)=W.sub.1 /W.sub.0 ×100

wherein W₀ is a weight of the sample and W₁ is a weight of maleicanhydride in the titrated sample.

Successively, MPLA-1 prepared as above, unmodified powdery polylacticacid having a weight average molecular weight of 130,000 (PLA:manufactured by Mitsui Chemicals Inc.) and 200 mesh pass wood flour(cellulosine) were weighted into a beaker at a prescribed ratio shown inTable 1 in a total amount of 26 g, thoroughly mixed and poured over 5minutes into a labo-plastomill (manufactured by Toyo Seiki Co.)temperature-conditioned at 180° C. and equipped with blades rotating tothe reverse direction each other at a rate of 30 rpm. The mass wassuccessively kneaded at the same condition for 15 minutes.

Next, the kneaded mass thus obtained was compression molded at 200° C.for 0.5 minutes to obtain a film having a thickness of 0.4 mm.Rectangular specimens having dimensions of 80 mm×5 mm were prepared fromthe film, and tensile strength properties and heat flow properties wereevaluated. Results are illustrated in Table 2.

Comparative Example 1

Powdery polylactic acid having a weight average molecular weight of130,000 (PLA: manufactured by Mitsui Chemicals Inc.) and 200 mesh passwood flour (cellulosin) were weighed into a beaker in an amount of 13.0g, respectively. These two materials were thoroughly mixed and pouredover 5 minutes into a labo-plastomill (manufactured by Toyo Seiki Co.).The labo-plastomill was controlled at 180° C. and stirring bladesrotated at a rate of 30rpm to the reverse direction each other. The masswas successively kneaded under the same condition for 15 minutes.

Next, the kneaded mass obtained was compression molded at 200° C. for0.5 minutes to prepare a film having a thickness of 0.4 mm. Rectangularspecimens having dimensions of 80 mm×5 mm were prepared from the filmand tensile strength properties and heat flow properties were evaluated.Results are shown in Table 1 and Table 2.

                  TABLE 1                                                         ______________________________________                                                 Composition                                                            (parts by weight)                                                                      Component E                                                                 Component A                                                                            Component D                                                                              Component B                                      ______________________________________                                        Example  1     45         5        50                                            2 40 10 50                                                                    3 35 15 50                                                                    4 30 20 50                                                                    5 25 25 50                                                                    6 20 30 50                                                                    7 15 35 50                                                                    8 10 40 50                                                                    9 5 45 50                                                                     10 0 50 50                                                                   Comparative 1 50 0 50                                                         Example                                                                     ______________________________________                                         Component A: unmodified PLA                                                   Component B: wood flour                                                       Component D: modified PLA (MPLA1)                                             Component E: mixture of unmodified PLA and modified PLA (MPLA1)          

                  TABLE 2                                                         ______________________________________                                                Evaluation results                                                                      Elon-                                                         Tensile gation Tensile Melt Heat flow                                         strength at break Modulus Viscosity Tempra-                                   (MPa) (%) (Mpa) (poise) ture (° C.)                                  ______________________________________                                        Example 1     48.2    1.46  2521.2 9099   180.0                                  2 48.3 1.65 2477.1 8042 180.0                                                 3 41.2 1.83 1704.2 6059 175.0                                                 4 43.1 2.03 1500.0 5531 170.0                                                 5 49.8 2.58 2496.2 5421 175.0                                                 6 41.3 1.97 3082.3 1767 170.0                                                 7 44.0 2.38 2659.5 4433 170.0                                                 8 39.3 1.93 2744.9 5571 165.0                                                 9 45.8 2.25 2717.0 4298 165.0                                                 10 39.3 2.59 2142.0 1968 170.0                                               Comparative 1 29.2 1.29 2504.5 6756 180.0                                     Example                                                                     ______________________________________                                    

The same procedures as Examples 1-10 were carried out except that 200mesh pass wood flour (cellulosin) was replaced by corn starch. own inTable 3 and Table 4.

Example 20

The same procedures as Example 1 were carried out except that 4.6 partsby weight of maleic anhydride and 0.1 part by weight of dicumyl peroxidewere used. Modified PLA (MPLA-2) was obtained by carrying out thereaction similarly to Example 1. After purifying by the same proceduresas Example 1, the ratio of maleic acid addition was measured bytitration. The addition ratio was 1.3% by weight.

The procedures as Example 10 were carried out except that 200 mesh woodflour was replaced by corn starch and MPLA-1 was replaced by MPLA-2.Results are shown in Table 3 and Table 4.

Comparative Example 2

The same procedures as Comparative Example 1 were carried out exceptthat 200 mesh pass wood flour (Cellulosin)(component B) was replaced bycorn starch. Results are shown in Table 3 and Table 4.

                  TABLE 3                                                         ______________________________________                                                 Composition                                                            (parts by weight)                                                                      Component E                                                                 Component A                                                                            Component D                                                                              Component B                                      ______________________________________                                        Example  11    45         5        50                                            12 40 10 50                                                                   13 35 15 50                                                                   14 30 20 50                                                                   15 25 25 50                                                                   16 20 30 50                                                                   17 15 35 50                                                                   18 10 40 50                                                                   19 5 45 50                                                                    20 0 50 50                                                                   Comparative 2 50 0 50                                                         Example                                                                     ______________________________________                                         Component-A: unmodified PLA                                                   ComponentB: starch                                                            ComponentD: modified PLA (MPLA1)                                              ComponentE: mixture of unmodified PLA and modified PLA (MPLA1).               Example 20 alone used modified PLA (MPLA2).                              

                  TABLE 4                                                         ______________________________________                                                Evaluation results                                                                      Elon-                                                         Tensile gation Tensile Melt Heat flow                                         strength at break Modulus Viscosity Tempra-                                   (MPa) (%) (Mpa) (poise) ture (° C.)                                  ______________________________________                                        Example 11    31.2    2.04  1821.2 14320  175.0                                  12 33.0 2.20 1560.3 8828 170.0                                                13 35.3 2.35 1884.3 7103 170.0                                                14 42.2 2.70 2146.0 6863 170.0                                                15 31.2 2.15 1943.6 4083 170.0                                                16 31.1 2.19 1533.1 1960 170.0                                                17 23.2 1.76 1860.1 994 170.0                                                 18 36.1 2.09 1533.9 1361 165.0                                                19 31.4 1.71 1529.8 360 165.0                                                 20 32.1 2.01 1610.1 192 165.0                                                Comparative 2 28.3 2.17 1498.8 14830 175.0                                    Example                                                                     ______________________________________                                    

Examples 21-24

The same procedures as Examples 1-10 were carried out except that 200mesh pass wood flour (Cellulosin) was replaced by cellulose fine powder(Wattman CF-11). Results are illustrated in Table 5 and Table 6.

Comparative Example 3

The same procedures as Comparative Example 1 were carried out exceptthat 200 mesh pass wood flour (Cellulosin) was replaced by cellulosefine powder (Wattmen CF-11). Results are illustrated in Table 5 andTable 6.

                  TABLE 5                                                         ______________________________________                                                 Composition                                                            (parts by weight)                                                                      Component E                                                                 Component A                                                                            Component D                                                                              Component B                                      ______________________________________                                        Example  21    45         5        50                                            22 40 10 50                                                                   23 20 30 50                                                                   24 0 50 50                                                                   Comparative 3 50 0 50                                                         Example                                                                     ______________________________________                                         Component A: unmodified PLA                                                   Component B: cellulose fine powder                                            Component D: modified PLA (MPLA1)                                             Component E: mixture of unmodified PLA and modified PLA (MPLA 1)         

                  TABLE 6                                                         ______________________________________                                                Evaluation results                                                                      Elon-                                                         Tensile gation Tensile Melt Heat flow                                         strength at break Modulus Viscosity Tempra-                                   (MPa) (%) (Mpa) (poise) ture (° C.)                                  ______________________________________                                        Example 21    56.2    2.21  3620   3720   170                                    22 56.4 2.30 3818 3653 170                                                    23 55.9 2.19 3960 3620 170                                                    24 26.6 2.23 3730 3623 170                                                   Comparative 3 54.6 2.12 3514 15390 175                                        Example                                                                     ______________________________________                                    

Examples 25-27

In a prescribed proportion illustrated in Table 7, powdery polylacticacid having a weight average molecular weight of 130,000 (PLA:manufactured by Mitsui Chemicals Inc.), cellulose fine powder (componentB), maleic anhydride (component C) and dicumyl peroxide (component X)were weighed into a beaker in a total amount of 26g, thoroughly mixedand poured over 5 minutes into the same labo-palstomill as used inExample 1. Successively, kneading was carried out for 15 minutes underthe same conditions as Example 1.

The kneaded mass thus obtained was compression molded by the sameprocedures as Example 1 to prepare a film having a thickness of 0.4 mm.Rectangular specimens having dimensions of 80 mm×5 mm were cut from thefilm and tensile properties and heat flow properties were evaluated.Results are shown in Table 8.

                  TABLE 7                                                         ______________________________________                                               Composition                                                              (parts by weight)                                                                    Component Component Component                                                                             Component                                  A B C X                                                                     ______________________________________                                        Example                                                                              25    50        50      2.5     0.38                                      26 50 50 5.0 0.75                                                             27 50 50 7.5 1.13                                                            Compara- 30 50 50 0 0                                                         tive                                                                          Example                                                                     ______________________________________                                         Component A: unmodified PLA                                                   Component B: cellulose fine powder                                            Component C: maleic anhydride                                                 Component X: dicumyl peroxide                                            

                  TABLE 8                                                         ______________________________________                                                Evaluation results                                                                      Elon-                                                         Tensile gation Tensile Melt Heat flow                                         strength at break Modulus Viscosity Tempra-                                   (MPa) (%) (Mpa) (poise) ture (° C.)                                  ______________________________________                                        Example 25    58.0    2.46  3450   3868   170                                    26 64.6 2.27 4123 3624 170                                                    27 59.5 2.20 3980 2610 170                                                   Comparative 3 54.6 2.12 3514 15390 175                                        Example                                                                     ______________________________________                                    

When Examples 1-10 and Comparative Example 1 are compared in theevaluation results of Table 1 and Table 2, it is understood thatsubstitution of maleic anhydride modified polylactic acid for a portionof unmodified polylactic acid brings 1.7 times increase at maximum inthe tensile strength of the molded film. Moreover, it is quitesurprising that the similar level of tensile strength increasing effectcan be obtained by merely substituting 20% by weight of unmodifiedpolylactic acid for maleic anhydride modified polylactic acid. Theinformation strongly suggests that maleic anhydride modified polylacticacid functions as a reactive compatibilyzer.

That is, it is suggested that the maleroyl group of maleic anhydridemodified polylactic acid reacts with a hydroxyl group on the surface ofwood flour during the kneading at 180° C. for 20 minutes and thatpolylactic acid is grafted by ester linkage on the surface of woodflour. And the intersurface adhesion in the processing article is alsosuggested to enhance between wood flour filler and matrix resin, thatis, modified or unmodified polylactic acid. Further, heat flowprocessing ability is not impaired and high processing ability ismaintained.

When Example 11-20 are compared with Comparative Example 2 in theresults of Table 3 and Table 4, that is, as compared with usingunmodified polylactic acid alone as a matrix resin, substitution of aportion of unmodified polylactic acid for maleic anhydride modifiedpolylactic acid is understood to bring remarkable increase in thestrength of the obtained molded film which reaches to 1.49 times at amaximum.

When Examples 1-20 are compared with Comparative Examples 1 and 2 in theresults of Tables 1-4, melt viscosity becomes lower with increase in thecontent of maleic anhydride modified polylactic acid (component D) inthe matrix resin of component E.

Addition of modified polylactic acid (component D) to the matrix resinof component E results in a composite having high processing ability anddegree of the processing ability enhances with increase in the modifiedpolylactic acid content. Dispersibility of the filler (component-B) isalso improved by addition of modified polylactic acid to the matrixresin, component E.

As mentioned above, these results are considered to further stronglyprove the consideration that maleic anhydride modified polylactic acidacts as a reactive compatibilyzer.

Further, as clearly understood from the results of Table 7 and Table 8,a molded product having a high tensile strength can be obtained byheating and kneading powdery polylactic acid (component A), cellulosefine powder (component B), and maleic anhydride (component C) in thepresence of a radical initiator. The result also proves presence of acovalent bond between component A and component B through component C.

What is claimed is:
 1. A preparation process of a composite resincomposition comprising obtaining modified aliphatic polyester (componentD) having aliphatic hydroxycarboxylic acid units by heating and reacting100 parts by weight of aliphatic polyester resin (component A) havingaliphatic hydroxycarboxylic acid units and 1-30 parts by weight ofunsaturated carboxylic acid or a derivative thereof (component C) in thepresence or absence of a solvent in the presence of a radical generator,and successively heating and kneading a mixture of 5-95% by weight of amixture (component E) of 0-95 % by weight of component A and 100-5 % byweight of component D, and 95-5 % by weight of one or more biomassmaterials (component B) selected from the group consisting of celluloseand lignocellulose.
 2. The preparation process of a composite resincomposition according to claim 1, wherein the unsaturated carboxylicacid or a derivative thereof (component C) is maleic acid or maleicanhydride.
 3. The preparation process of a composite resin compositionaccording to claim 1, wherein the aliphatic polyester resin (componentA) having aliphatic hydroxycarboxylic acid units is polylactic acid. 4.The preparation process of a composite resin composition according toclaim 2, wherein the aliphatic polyester resin (component A) havingaliphatic hydroxycarboxylic acid units is polylactic acid.
 5. Acomposite resin composition comprising a mixture (component E) of 0-95 %by weight of aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units and 100-5 % by weight of modified aliphaticpolyester resin (component D) having aliphatic hydroxycarboxylic acidunits which is obtained by reacting 100 parts by weight of component Awith 1-30 parts by weight of unsaturated carboxylic acid or a derivativethereof (component C), and one or more biomass materials (component B)selected from the group consisting of cellulose and lignocellulose,wherein said composite resin composition comprises a component obtainedby covalently bonding a portion or the whole of component A andcomponent B through component C and component B is 5-95 % by weight ofcomponent B and component D or component E.
 6. The composite resincomposition according to claimed 5, wherein the unsaturated carboxylicacid or a derivative thereof (component C) is maleic acid or maleicanhydride.
 7. The composite resin composition according to claim 5,wherein the aliphatic polyester resin (component A) having aliphatichydroxycarboxylic acid units is polylactic acid.
 8. The composite resincomposition according to claim 6, wherein the aliphatic polyester resin(component A) having aliphatic hydroxycarboxylic acid units ispolylactic acid.
 9. A method of preparing a formed item comprisingheat-extruding the composite resin composition according to claim 5 intothe formed item.
 10. A formed item comprising the composite resincomposition according to claim
 5. 11. An artificial wood comprising thecomposite resin composition according to claim
 5. 12. A containercomprising the composite resin composition according to claim
 5. 13. Afilm comprising the composite resin composition according to claim 5.14. A sheet comprising the composite resin composition according toclaim
 5. 15. A tray comprising the composite resin composition accordingto claim
 5. 16. A foam comprising the composite resin compositionaccording to claim 5.